Pneumatic conveyor means for fragile elements



19, 1965 J. c. BENESH ETAL 3,212,820

PNEUMATIC CONVEYOR MEANS FOR FRAGILE ELEMENTS Original Filed Jan. 12,1962 WITNESSES: INVENTORS Joseph C. Benesh and Edward F? Lovernoich.

United States Patent 3 Claims. ((11. 302-2) This application is acontinuation of Serial No. 165,816, filed January 12, 1962, assigned tothe same assignee, and now abandoned.

This invention relates to the art of conveying fragile elements, andmore particularly to improved pneumatic conveying apparatus forinserting and assembling fragile heater elements in the cathodes ofelectron discharge devices.

In the manufacture of electron tubes, the insertion of the heaterelements into the cathode sleeves presents a delicate assemblyoperation. Heretofore, it has been conventional to perform this delicateassembling operation manually. These heater elements take differentforms, such as a folded strand wire construction, similar to that shownand described in US. Patent 2,913,805, issued to C. F. Miller et al. onNovember 24, 1959. Also the heater elements may be in the form of acontinuous coil of resistance wire, such as tungsten wire, bent to thehairpin shape. In both instances the wire is coated with an insulatingmaterial. The folded type is the most commonly used in the manufactureof electron discharge tubes and presents the greatest difficulty inassembling operations. The insulating coating on such heaters is usuallymade of refractory material which is relatively brittle and, therefore,requires very delicate assembly operations.

Although heretofore pneumatic conveyor devices have been employed forinserting these delicate heater elements into cathode sleeves, theseprior devices have had certain disadvantages which has necessitated theestablishment of many expensive controlled dimensional factors andproper conditions in order to ensure the success of the assemblingoperation.

It is, therefore, a primary object of this invention to provide animproved conveyor means for conveying and guiding lightweight fragileheater elements from a point of convenience into cathode sleeves.

Another object is to provide improved means of the type generallydescribed for conveying lightweight, delicate articles into a finalassembled position in which they are held by friction.

A further object is to provide an improved apparatus of the typedescribed in which pneumatic conveying means is provided for conveyingand directing the light fragile articles toward a final position inwhich the conveying medium is disassociated from the conveyed article,the latter being permitted to proceed to its final position under theforce of its own momentum.

Another object is to provide a novel and improved pneumatic conveyingapparatus for conveying a fragile lightweight article from a point ofconvenience to a predetermined assembled position in which there is anaccelerating section axially aligned with a decelerating section whereinthe article is accelerated to a point where the conveying medium isdirected away from the axis of the sections permitting the article tocontinue in its initial path under its own momentum, the article beingdecelerated by the pneumatic medium flowing in the opposite direction inthe decelerating section.

The novel features that are considered characteristic of this inventionare set forth with particularity in the appended claims. The inventionitself, however, both as to its organization and method of operation aswell as additional objects and advantages will best be understood fromthe following description when read in connection with the accompanyingdrawing, in which the single figure is an elevational view, partially insection, of a schematic representation of an embodiment of the presentinvention.

Briefly speaking, the present invention provides pneumatic conveyor andassembling means for lightweight fragile articles, such as heaterelements for cathodes of electron discharge devices comprising,pneumatic means for conveying and imparting suflicient acceleration tosuch articles for carrying them under their own momentum through aportion of their path from a point of convenience to their assembledposition with another part, appropriate means being provided near theend of the pneumatic conveyor path for disassociating the acceleratinginfluence of the pneumatic conveyor medium from the articles andapplying a decelerating pneumatic influence on said articles, thedecelerating pneumatic influence and the friction between the articleand the part being relied upon to determine the final assembledposition. A salient feature resides in the means for providing suchacceleration and deceleration without having the pneumatic mediumdisturb the articles after reaching their final assembled position.

In the embodiments of the invention illustrated in the drawings, thereis shown pneumatic conveyor apparatus having a passageway for conveyingan article, such as a heater element 1 for an electron discharge device,from a .place of convenience to its final assembled position, such as inthe cathode sleeve 2 of such device. The passageway may be considered ascomprising an acceleration section 3 and a decelerating section 4 whichare in axial alignment with each other. Suitable means are provided forcausing a pneumatic conveying medium, preferably air, to flow throughthese two sections in opposite directions, the air being caused to flowaway from the adjacent ends of the sections in such manner that the pathof the conveyed article will not be deviated from the axis of thepassage. The accelerating section 3 is the longer of the two sections byan amount suflicient to enable it to im part sufficient momentum to theconveyed articles to carry them through the deceleration section 4 andto a gentle stop in the final assembled position in the cathode sleeve2, both ends of which are open.

To this end, the accelerating section 3 is in the form of an entranceportion or launching tube 10 having a funnel 11, constituting theloading tip, into which the fragile heater elements may be placed by anoperator. The decelerating section 4 includes a discharge portion ornozzle 12, a funnel bushing or guide member 13 and a portion of thecathode sleeve 2 all of which are arranged in axial alignment and withthe mouths of the nozzle 12 and funnel bushing 13 disposed toward thelaunching tube 10. The funnel bushing 13 is provided with a recess 15which serves as a guide for properly aligning a cathode sleeve 2 withthe passage in the bushing 13. In the embodiment shown in the drawing, asource of negative pressure is utilized for causing high velocity airstreams to flow from the outer respective ends of the tube 10 and thenozzle 12 toward their respective adjacent inner ends. To accomplishthis the tube 10 and the nozzle 12 are in airtight engagement with thewalls of a chamber 14 which is connected to a source of negativepressure, such as a vacuum pump 16 or an equivalent device, through asuitable conduit 17. The capacity of the vacuum pump 16 is so related tothe circular cross sectional area of the launching tube 10 and that ofthe passage in the nozzle 12 that there is a low pressure zonemaintained around the inner end of the launching tube and the mouth ofthe nozzle 12. The volume of the chamber 14 is of sufficient magnitudethat the high velocity air flowing from the inner ends of the tube 10and the mouth of the nozzle 12 expands uniformly radially outwardly intothe chamber. Because the air expands radially in all directions, it willnot cause articles being conveyed, such as a heater element 1, todeviate from its projected path through the space between the inner endof tube 10 and the mouth of the nozzle 12.

The mouth of the funnel bushing 13 is spaced from the outer end of thenozzle 12, as at gap 18, so that the air flowing into the outer end ofthe nozzle 12, as represented by the arrows 19, will not develop a lowpressure zone at the mouth of the bushing and, therefore, will not tendto withdraw a heater element after it has come to rest in the open-endedcathode sleeve 2 when the latter is in gas-tight engagement with thebushing 13.

The capacity of the vacuum pump 16 is so chosen in relation to the otherfactors, such as the relative length and size of the passages in thetube 10, the nozzle 12 and the friction between a heater element 1 andthe inside of cathode sleeve 2 that the heater element entering theloading tip will be drawn into the tube 10 at high velocity and will beconveyed into the cathode sleeve where it will come to a gradual andgentle stop at the desired point under the final arresting action of thefriction between the heater element and the inside of the sleeve. Merelyfor the purpose of giving the parameters of a working example and not byway of limitation, apparatus of the type described performed in thedesired manner when transferring heater elements which were folded intobundles approximately .025 inch in diameter and the diameter of thepassage in the launching tube 10 was approximately .069 inch indiameter, the diameter of the passage in nozzle 12 was approximately.035 inch in diameter, the passage in the funnel bushing 13 wasapproximately .031 inch in diameter and the inside dimension of thecathode sleeve was .035 inch. The capacity of the vacuum pump 16 in thatinstance, was such as to maintain a negative pressure of approximately21 inches of mercury in the chamber 14.

Since a heater element is resilient and is in the form of a foldedbundle when presented to the launching tube 10 it has a tendency toexpand against the inside of the tube. It is desired to have the insidedimension of the tube 10 a little larger than the passages in the nozzleand the funnel bushing in order to reduce the friction and permit theheater element to gain sufiicient momentum to carry it to its finalposition. The passage in the funnel bushing 13 is preferably slightlysmaller than the inside diameter of the cathode sleeve to insure thatfragile heater elements will not be damaged by striking the edge of thesleeve.

In the operation of the apparatus of this invention, cathode sleeves ofelectron discharge devices, such as that illustrated at 2, are presentedmanually in a sequential manner in substantially gas-tight engagementwith the bottom of the recess of the funnel bushing 13. In timedrelation with the presentation of cathode sleeves in engagement with thebushing 13, an operator manually places a heater element 1, in thefolded bundle shape, in front of the mouth of the funnel 11 from whereit is conveyed at accelerated velocity by the air stream through thelaunching tube 10. The momentum of the heater element projects it intothe decelerating nozzle 12 where it is subjected to the deceleratingaction of the air stream flowing in the opposite direction. Because theair stream expands uniformly radially outwardly in the chamber 14- inthe space between the end of the launching tube and the mouth of thenozzle, the heater element being conveyed will not be deflected from itspath along the axis of the pneumatic conduit passageway. The heaterelement being conveyed will proceed across the air gap 18 between theouter end of the nozzle 12 and the mouth of the funnel bushing 13. Sincethe gap 18 is open to the atmosphere uniformly around the axis, the pathof the projected heater element will not be deflected. The deceleratingaction of the stream of air in the nozzle 12 is supplemented by thefriction between the heater element and the inside surface of a cathodesleeve in bringing the heater element to a gentle stop in the desiredassembled relation without damage to the fragile heater element.

While the invention has been shown in but one form, it will be obviousto those skilled in the art that it is not so limited, but issusceptible of various changes and modifications without departing fromthe spirit thereof.

We claim as our invention:

1. Pneumatic conveying apparatus for assembling an article into a hollowportion of a sleeve, said apparatus comprising a first means fortransporting said article from a predetermined position into said hollowportion, said first means including an entrance portion associated withsaid predetermined position and a discharge portion, a second means forcreating a vacuum intermediate said entrance and discharge portions toprovide a first flow of conveying medium to compel said article throughsaid en trance portion and to provide a second flow of conveying mediumthrough said discharge portion in a direction opposite to that of saidfirst flow, and a third means having an enlarged opening and beingspaced from and aligned with said discharge portion to substantiallydisassociate said hollow portion of said sleeve from said second flow ofconveying medium through said discharge portion.

2. Pneumatic conveying apparatus for assembling an article into an openended sleeve, said apparatus comprising a conduit means for transportingsaid article from a predetermined position into said sleeve, saidconduit means including an entrance portion associated with saidpredetermined position and a discharge portion, a vacuum producing meansoperatively disposed intermediate said entrance and discharge portionsto establish first and second flows of conveying medium respectivelythrough said entrance and discharge portions in opposite directions, anda guide member having an enlarged inlet to receive said article andbeing spaced from and aligned with said discharge portion tosubstantially isolate said sleeve from said second flow of conveyingmedium through said discharge portion and to thereby prevent thewithdrawal of said article from said sleeve.

3. Pneumatic conveying apparatus for assembling an article into an openended sleeve, said apparatus comprising a first means including atubular conduit for conveying said article from a predetermined positioninto said sleeve, second means operatively associated with said firstmeans for creating a flow of conveying medium in said first means and athird means including a guiding member having an aperture therein, saidguiding member being associated with said first means to inhibit thedevelopment of a low pressure zone or" said conveying medium at saidaperture and to thereby prevent the withdrawal of said article from saidopen ended sleeve after the insertion of said article, said aperturebeing aligned with said tubular conduit to direct said article into saidopened ended sleeve.

References Cited by the Examiner UNITED STATES PATENTS 2,842,923 7/58Kjellsen 302-2 SAMUEL F. COLEMAN, Primary Examiner.

ANDRES H. NIELSEN, Examiner.

1. PNEUMATIC CONVEYING APPARATUS FOR ASSEMBLING AN ARTICLE INTO A HOLLOWPORTION OF A SLEEVE, SAID APPARATUS COMPRISNG A FIRST MEANS FORTRANSPORTING SAID ARTICLE FROM A PREDETERMINED POSITION INTO SAID HOLLOWPORTION, WITH FIRST MEANS INCLUDING AN ENTRANCE PORTION ASSOCIATED WITHSAID PEREDETERMINED POSITION AND A DISCHARGE PORTION, A SECOND MEANS FORCREATING A VACUUM INTERMEDIATE SAID ENTRANCE AND DISCHARGE PORTIONS TOPROVIDE A FIRST FLOW OF CONVEYING MEDIUM TO COMPET SAID ARTICLE THROUGHSAID ENTRANCE PORTION AND TO PROVIDE A SECOND FLOW OF CONVEYING MEDIUMTHROUGH SAID DISCHARGE PORTION IN A DIRECTION OPPOSITE TO THAT OF SAIDFIRST FLOW, AND A THIRD MEANS HAVING AN ENLARGED OPENING AND BEINGSPACED FROM AND ALIGNED WITH SAID DISCHARGE PORTION TO SUBSTANTIALLYDISASSOCIATE SAID HOLLOW PORTION OF SAID SLEEVE FROM SAID SECOND FLOW OFCONVEYING MEDIUM THROUGH SAID DISCHARGE PORTION.